1. Field of the Invention
The present invention pertains to multi-circuit electrical connector arrangements which are mounted to an electronic device such as a printed circuit board, connector plug, or connector receptacle.
2. Description of the Prior Art
Multi-circuit electrical connectors of the type adapted for mounting on a printed circuit board or the like typically include a plurality or electrical terminals disposed within a unitary dielectric housing. Such housings typically totally surround the terminals, and provide inter-terminal barriers of insulation material.
Difficulties in maintaining the pitch or centerline spacing of terminals has been encountered with increasing connector miniaturization. Difficulties in pitch control arise because of the inherent physical properties of the inter-terminal dielectric material of which the housings are made. For example, it is well known that many plastics tend to swell somewhat with increasing humidity. Also, thicknesses of the metal stock from which terminals are formed can vary slightly from terminal to terminal. These and other like processes tend to deteriorate the dimensional tolerance of connector assemblies. Nonetheless, there is an increasing need to reduce the pitch or centerline spacing of electrical connector assemblies, including not only assemblies mounted on a printed circuit board, but also the connector assemblies found in connector plugs, connector receptacles, and other electronic devices.
Other difficulties have been encountered in providing connector arrangements for liquid crystal displays and the like. A liquid crystal display is typically a thin wafer-like electronic package encapsulated in glass. Because of its essentially two-dimensional configuration (i.e. its relatively thin construction), and because displays are elongated along a direction parallel to the mounted surface, it is difficult to provide effective simultaneous electrical connection with all segments of the display, while preventing stressing of the display which would cause the glass package to crack.
One arrangement typically provided for overcoming these difficulties is popularly known in the art as a "Zebra strip". An example of this connector arrangement is shown in U.S. Pat. No. 4,008,300 issued to Timothy Ponn. A method of producing this connector arrangement includes the steps of taking a dielectric sheet of resilient material such as natural or synthetic non-conductive rubber, and cutting the sheet to form a gasket-like frame against which the display is pressed. The cut frame is perforated with a series of holes for receiving discrete rod-like portions of resilient conductive material. The conductive material is in effect pressed into or otherwise formed within the dielectric rubber sheet. The display, when pressed against the dielectric sheet, is brought into intimate contact with the resilient conductive portions. Electrical leads of the display can conveniently be brought to an outside mating surface so as to be maintained in pressed engagement with the resilient conductive portions.
A convenient method for forming the conductive portions is to fill the holes with a slurry of electrically conductive material which is then allowed to cure, with constriction of the holes applying sufficient radial force to the resilient conductor portions to cause them to bulge outwardly beyond the surfaces of the dielectric rubber sheet. Such arrangements are, however, limited to compressive engagement with coextensive planar electronic devices.
More importantly, in commonly assigned U.S. Pat. No. 577,922, there is described a connector assembly adapted to electrically mate with an electronic device having closely spaced circuits, and a method for making a connector assembly. The connector assembly includes a generally linear terminal array having a plurality of spaced-apart metal terminals with dielectric means disposed on each terminal to provide insulation between adjacent terminals. Each terminal has a portion adapted to mate with a corresponding one of the closely spaced circuits on the electronic device.